Search found 62 matches
- Sun Mar 17, 2019 7:05 pm
- Forum: *Enzyme Kinetics
- Topic: How do you tell if something is a catalyst vs an intermediate?
- Replies: 16
- Views: 5985
Re: How do you tell if something is a catalyst vs an intermediate?
Intermediates are consumed in the reaction
- Sat Mar 16, 2019 1:41 am
- Forum: Calculating Work of Expansion
- Topic: Adiabatic proceses
- Replies: 1
- Views: 419
Adiabatic proceses
How do you find final temperature in an adiabatic irreversible expansion of gas?
- Fri Mar 15, 2019 10:31 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 4
- Views: 662
Catalysts
Can catalysts be part of the rate law?
- Wed Mar 13, 2019 3:56 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst equation
- Replies: 1
- Views: 417
Re: Nernst equation
I believe you meant E=E0-.05916/n logQ. We get 0.05916 from the gas constant (R) x room temperature in kelvin (K) x 2.303logx (which is the conversion from natural log to log base 10) all divided by Faraday's constant. So this equation is the same as E=E0-RT/nf lnQ only when temperature is at room t...
- Tue Mar 12, 2019 8:02 pm
- Forum: Balancing Redox Reactions
- Topic: Coefficients
- Replies: 3
- Views: 1101
Re: Coefficients
No coefficients do not affect oxidation numbers, it only affects the amount of electrons you have in the reaction
- Tue Mar 12, 2019 5:35 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Largest E°cell question test #2
- Replies: 4
- Views: 570
Re: Largest E°cell question test #2
You would have to pick is the biggest reducing agent and the biggest oxidizing agent.
- Tue Mar 12, 2019 5:32 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Test 2 #6 Ordering Reducing/Oxidizing Power
- Replies: 3
- Views: 544
Re: Test 2 #6 Ordering Reducing/Oxidizing Power
To add, for part C you would just simply look at the biggest reducing and biggest oxidizing agent.
- Tue Mar 05, 2019 5:20 pm
- Forum: First Order Reactions
- Topic: Exponential Curve
- Replies: 6
- Views: 670
Exponential Curve
Why does a plot of [Reactants] vs time for a 1st order reaction give an exponential curve?
- Tue Mar 05, 2019 5:10 pm
- Forum: Zero Order Reactions
- Topic: Initial reactions rates
- Replies: 3
- Views: 472
Initial reactions rates
Why do we study initial reaction rates as a function of only reactants?
- Fri Mar 01, 2019 10:00 am
- Forum: Balancing Redox Reactions
- Topic: Strength of reducing agent
- Replies: 10
- Views: 1954
Re: Strength of reducing agent
The smallest (more negative) Reduction potential is a stronger reducing agent
- Fri Feb 22, 2019 10:32 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Electrode Potential
- Replies: 2
- Views: 292
Electrode Potential
Why is electrode potential an intensive property and how will this affect the way we calculate it?
- Fri Feb 22, 2019 10:29 am
- Forum: Phase Changes & Related Calculations
- Topic: joules conversion factor
- Replies: 7
- Views: 1061
Re: joules conversion factor
To add, if you follow unit cancellation (8.314 J·K^-1·mol^-1) /( 8.206 x 10-2 L·atm·K-1·mol-1)= 101.3 J/(L*atm). These two values are given on the formula sheet and they are the gas constants (R) just given in different units. Depending in what units you are given or solve for you can convert using ...
- Fri Feb 22, 2019 10:21 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity
- Replies: 6
- Views: 706
Spontaneity
How does Gibbs free energy relate to spontaneity and stability of a reaction?
- Thu Feb 14, 2019 1:09 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 1 atm to 101.3 J/(atm*L)
- Replies: 2
- Views: 1589
Re: 1 atm to 101.3 J/(atm*L)
Or if you follow unit cancellation (8.314 J·K^-1·mol^-1) /( 8.206 x 10-2 L·atm·K-1·mol-1)= 101.3 J/(L*atm). These two values are given on the formula sheet and they are the gas constants (R) just given in different units.
- Thu Feb 14, 2019 12:46 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Molar and specific heat capacity
- Replies: 3
- Views: 430
Re: Molar and specific heat capacity
To add, molar heat capacity units should be J/(K*mol) and specific heat capacity units should be J/(K*grams). They are both intensive properties.
- Thu Feb 14, 2019 12:42 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Expansion of a system
- Replies: 8
- Views: 1195
Expansion of a system
How can one tell if a system is expanding or not? What criteria do we look for?
- Mon Feb 11, 2019 12:16 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isothermal reactions and delta U
- Replies: 1
- Views: 271
Isothermal reactions and delta U
If delta U equals 0, does it always mean it is an isothermal process, regardless if it is reversible or irreversible?
- Fri Feb 08, 2019 10:30 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Delta U
- Replies: 3
- Views: 389
Re: Delta U
Delta U is the change in internal energy. Delta U is used to see the change of internal energy due to the transfer of energy through heat or work.
- Fri Feb 08, 2019 10:21 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: delta H
- Replies: 1
- Views: 284
Re: delta H
Delta H represent the change of enthalpy of system. Basically, assuming a constant pressure, delta H describes a systems change in heat. A positive delta H represents that the system absorbs heat and a negative delta H represents that the system releases heat.
- Sat Feb 02, 2019 9:13 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy in Reversible Process
- Replies: 2
- Views: 242
Re: Entropy in Reversible Process
The entropy could vary in different parts of the system. But the total change of the system is 0. The inside and outside of the the system does not change in reversible processes.
- Sat Feb 02, 2019 9:07 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Biological Systems
- Replies: 3
- Views: 429
Biological Systems
Why is it in biological systems, delta U and delta H are the same.
- Sat Feb 02, 2019 9:01 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat
- Replies: 6
- Views: 576
Re: Heat
Yes, when heat is absorbed from the solution, q will be negative. In other words, the reaction absorbs heat from the solution and the reaction is endothermic. However, q for the reaction will be positive,
- Fri Jan 25, 2019 10:26 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding Inert Gas
- Replies: 10
- Views: 4592
Adding Inert Gas
I understand that when pressure increases by adding inert gas, there is no effect on the reaction. But why is this? Is it because the inert gas affects the whole reaction ( both products and reactants) equally?
- Fri Jan 25, 2019 10:22 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Delta H
- Replies: 4
- Views: 440
Re: Delta H
To add, when delta H is positive that means that there is more enthalpy (heat) in the products than in the reactants. This means that heat is required to be added into the reaction to produce the products.
- Tue Jan 22, 2019 6:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Stability
- Replies: 1
- Views: 147
Stability
When given two reactions (with K) how can we determine which is thermodynamically more stable relative to its atoms?
- Thu Jan 17, 2019 10:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Relationship between pH and pKa
- Replies: 2
- Views: 356
Re: Relationship between pH and pKa
pH is the amount of hydrogen ions in an aqueous solution. pKa is the acid dissociation constant which tells you at what degree the acid will dissociate. It can also tell which side the equilibrium will favor. Basically, pKa tell you what the pH needs to be in order for the acid to donate an electron.
- Thu Jan 17, 2019 9:02 pm
- Forum: Ideal Gases
- Topic: [Products] over [Reactants] cancellations
- Replies: 3
- Views: 462
Re: [Products] over [Reactants] cancellations
In the cases with weak acids we can assume that Ka is very small and does not affect the reaction. (if Ka is less than 10^-3 or 10^-4 to be safe). It is important to remember that x is not 0, it just very small relative to the initial molar concentration that it has not affect on the reaction.
- Thu Jan 17, 2019 8:36 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Hydronium Concentration
- Replies: 3
- Views: 389
Hydronium Concentration
Why is it when [H3O+]<10^-7 the solution is considered neutral?
- Fri Jan 11, 2019 10:12 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chem equilibrium module 2
- Replies: 1
- Views: 141
Re: Chem equilibrium module 2
No, you do not need to use the ice table. You should use the ideal gas law to convert from concentration to partial pressure of reactants and products at equilibrium. Pv=nrt divide by v to get P=(n/v)(RT) this is the same as P=(concentration)(RT) where R is 8.206 × 10-2 L.atm.K-1.mol-1 and temperatu...
- Fri Jan 11, 2019 9:55 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Converting Kc to Kp
- Replies: 4
- Views: 1149
Re: Converting Kc to Kp
Just to clarify, Dn is the to total stoichiometric coefficients of the product - the total stoichiometric coefficient of the reactants. For example, if you had the reaction aA(g)+bB(g)----> cC(g)+dD(g) the Dn would be (c+d)- (a+b). Also, you are only allowed to use this when the product or the react...
- Wed Jan 09, 2019 4:32 pm
- Forum: Ideal Gases
- Topic: Audio Visual Test Question
- Replies: 1
- Views: 251
Re: Audio Visual Test Question
I believe you are talking about this question:A researcher fills a 1.00 L reaction vessel with 1.84 x 10-4 mol of BrCl gas and heats it to 500 K. At equilibrium, only 18.3 % of the BrCl gas remains. Calculate the equilibrium constant, assuming the following reaction is taking place. 2BrCl(g) ⇌ Br2 (...
- Fri Dec 07, 2018 1:33 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN
- Replies: 5
- Views: 804
Re: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN
Yes, I believe sig figs count only after the decimal point. For example, if the molarity .0023 is given the correct answer with sig figs is Ph=2.64 because the sig figs only count after the decimal point.
- Fri Dec 07, 2018 1:18 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Complexes
- Replies: 2
- Views: 185
Re: Coordination Complexes
A tetrahedral complex has 4 ligands at the corners of a tetrahedron. While a square planar complex has 4 ligands at the corners of a square. I hope I answered your question.
- Wed Dec 05, 2018 3:12 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 7
- Views: 628
Coordination Number
What is the difference between the oxidation number and the coordination number of a complex structure.
- Sun Dec 02, 2018 4:28 pm
- Forum: *Molecular Orbital Theory Applied To Transition Metals
- Topic: Transition Metals
- Replies: 5
- Views: 1840
Transition Metals
What properties of transition metals allow them to have many oxidation states?
- Sun Dec 02, 2018 12:38 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Lone pair location
- Replies: 3
- Views: 782
Re: Lone pair location
Lone pairs have a great repulsion strength. This means that lone pairs will repel the bonded pairs. For example, in H2O is not a linear shape because the 2 lone pairs repel the bonded pairs making the shape bent with 104.5 bond angles. In all, lone pairs repel bonded pairs. This makes the shapes &qu...
- Sun Dec 02, 2018 12:32 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: chelate
- Replies: 4
- Views: 475
Re: chelate
A chelate is a multi dentate ligand, meaning it is a complex containing a ligand that forms a ring of atoms the include the central metal atom. Therefore chelating ligands can bind cations tightly. They are stronger than coordinate compounds.
- Mon Nov 26, 2018 12:19 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Polar Bonds
- Replies: 3
- Views: 1729
Polar Bonds
How do polar bonds with dipoles cancel?
- Mon Nov 26, 2018 12:04 am
- Forum: Sigma & Pi Bonds
- Topic: Hybridization and Electron Configurations
- Replies: 3
- Views: 460
Re: Hybridization and Electron Configurations
Yes, it is necessary. By drawing the lewis structures you can see the number of regions of electron density and therefore, you can see the number of hybridization orbitals.
- Sun Nov 25, 2018 11:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 9
- Views: 719
Re: VSEPR
I think Lone pair Lone pair bonding is the strongest. Then it is long pair bonding pair. And the weakest is bonding pair bonding pair.
- Thu Nov 15, 2018 11:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion Strength
- Replies: 7
- Views: 706
Repulsion Strength
What does it mean when VSEPR models can predict distortions qualitatively but not quantitatively.
- Thu Nov 15, 2018 11:02 pm
- Forum: Ionic & Covalent Bonds
- Topic: H bonds and melting points
- Replies: 4
- Views: 643
Re: H bonds and melting points
H bonds have higher melting and boiling points because the intermolecular bonds are stronger. The H bond is a very strong bond because it is highly electronegative.
- Thu Nov 15, 2018 10:57 pm
- Forum: Dipole Moments
- Topic: Induced-dipole
- Replies: 5
- Views: 1857
Re: Induced-dipole
Induced dipoles occur when one molecule with a permanent dipole repels another molecule's electrons. A molecule with permanent dipole can induce a dipole in a similar neighboring molecule and cause mutual attraction. Any pair of molecules where one is a dipole and other is a non polar molecule can b...
- Thu Nov 15, 2018 10:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Vsepr Formula
- Replies: 7
- Views: 445
Re: Vsepr Formula
Molecule shapes can be predicted based on Lewis dot structure using the VSEPR theory. VSEPR stands for Valence Shell Electron Pair Repulsion. It states that electron pairs in the valence shell of an atom repel each other; their molecular geometry is the result of this repulsion. Basically, we use Le...
- Thu Nov 08, 2018 10:10 pm
- Forum: Dipole Moments
- Topic: Attractive Force
- Replies: 3
- Views: 212
Attractive Force
Does increasing the size of an atom result in a stronger attractive force or a weaker attractive force? Why?
- Thu Nov 08, 2018 10:01 pm
- Forum: Dipole Moments
- Topic: Polarizability
- Replies: 5
- Views: 381
Re: Polarizability
The greater the number of electrons, the less control the nuclear charge has on charge distribution, and thus the increased polarizability of the atom. Basically, polarizability depends on number of electrons and size of the atom or molecule.
- Thu Nov 01, 2018 11:32 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence electron
- Replies: 4
- Views: 333
Valence electron
How do you determine the number of valence electrons of elements in d block elements?
- Thu Nov 01, 2018 10:35 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electron Configuration
- Replies: 3
- Views: 338
Electron Configuration
What is the correct electron configuration of Br? [Ar] 3d10 4s2 4p5 or [Ar] 4s2 3d10 4p5?
- Thu Nov 01, 2018 10:26 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical Formulas with Masses
- Replies: 3
- Views: 436
Re: Empirical Formulas with Masses
1)Assume the sample is 100 grams
2)Convert to moles
3)divide the smallest mole amount
4)if necessary multiply the whole compound to get a whole number
5)add up the mass of the sample and it should match the mass of the compound given because it is the empirical formula
2)Convert to moles
3)divide the smallest mole amount
4)if necessary multiply the whole compound to get a whole number
5)add up the mass of the sample and it should match the mass of the compound given because it is the empirical formula
- Fri Oct 26, 2018 9:16 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bond
- Replies: 9
- Views: 908
Bond
In class, we discussed single, double, and triple bonds; however, is it possible to have a quadruple bond. And if so, what are the conditions?
- Fri Oct 26, 2018 9:02 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: nodal/radial planes
- Replies: 5
- Views: 589
Re: nodal/radial planes
To determine the number of nodal planes, we simply must know that in the s orbital there is 0 nodal planes, in the p orbital there is 1 nodal plane, and in the d orbital there are 2 nodal planes. In other words, the number of nodal planes is equal to the value of the angular momentum quantum number,...
- Thu Oct 25, 2018 2:20 pm
- Forum: Einstein Equation
- Topic: E=hv [ENDORSED]
- Replies: 52
- Views: 18426
E=hv [ENDORSED]
In the equation, E=hv, does E represent the energy of the photon or does it represent the energy required to remove an electron?
- Thu Oct 18, 2018 11:25 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Equation [ENDORSED]
- Replies: 2
- Views: 383
Heisenberg Equation [ENDORSED]
In the solution manual, the formula deltax= 1/2(h bar/m*deltav) is used. The book solution manual states that h bar is 1.054*10^-34J. My question is how is this derived and is this a constant?
- Thu Oct 18, 2018 10:40 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal Planes
- Replies: 2
- Views: 209
Nodal Planes
I know that this was mention in lecture; however in the d orbital, which d orbitals have nodal lobes on the plane and which have nodal planes on the axis?
- Thu Oct 18, 2018 10:34 pm
- Forum: *Shrodinger Equation
- Topic: Shrodinger Equation
- Replies: 2
- Views: 216
Re: Shrodinger Equation
I believe that we must only know the concept. We use a wave function to describe an electron in an atom. We must also know that a wave function like EM waves can take negative or positive values . This can be depicted by a sin or cos function.
- Thu Oct 11, 2018 11:28 pm
- Forum: Properties of Light
- Topic: Threshold Energy
- Replies: 11
- Views: 829
Re: Threshold Energy
Threshold energy is the minimum energy needed to eject an electron from a metal surface. The energy of the photon minus the threshold energy should equal to kinetic energy of the electron. This should satisfy the Law of conservation of energy.
- Thu Oct 11, 2018 10:50 pm
- Forum: Limiting Reactant Calculations
- Topic: Photoelectric Effect [ENDORSED]
- Replies: 2
- Views: 506
Photoelectric Effect [ENDORSED]
I understand that Dr. Lavelle explained this during lecture, however, I am still a bit confused. Can someone please explain how an electron is able to reach the detector if there is 0 Kinetic energy. Is there an attractive force of some sort?
- Thu Oct 11, 2018 10:39 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Mass percent composition [ENDORSED]
- Replies: 4
- Views: 888
Re: Mass percent composition [ENDORSED]
Mass percent composition is the concentration (mass) of an element in a compound or a component in a mixture. Mass percentage is calculated as the mass of a component divided by the total mass of the mixture, multiplied by 100%. For example, to find the mass percent of Carbon in glucose (C6H12O67) y...
- Thu Oct 04, 2018 3:07 pm
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 34756
Re: All students read this sig fig post [ENDORSED]
Shuyi Yu 1B wrote:When finding the molar mass in the periodic table how many sig figs do we use?
We use the amount of sig figs given on the specific periodic table.
- Thu Oct 04, 2018 3:02 pm
- Forum: SI Units, Unit Conversions
- Topic: mol vs. mmol
- Replies: 12
- Views: 2847
Re: mol vs. mmol
1mmol is equal to 1x10^-3 mol. the m in front mmol means milli or 10x^-3.
- Thu Oct 04, 2018 2:59 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Molar Masses
- Replies: 9
- Views: 585
Re: Molar Masses
No, we are given a periodic table on all tests, I believe.
- Tue Oct 02, 2018 10:26 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: stoichiometric terminology
- Replies: 3
- Views: 321
stoichiometric terminology
In the question," How many formula units of the compound are present in 5.15g?" What does formula units mean?